Rubber bearing with graduated damping behavoir

ABSTRACT

The present invention pertains to a rubber bearing with graduated damping characteristic, which comprises in the known manner essentially a preferably cylindrical or approximately cylindrical inner part, a tubular outer sleeve arranged coaxially around the inner part as well as a pressure body with chambers for a damping agent, which pressure body is arranged in a fixed manner between the inner part and the outer sleeve. The object of the present invention is to provide a rubber bearing which has a simple design and effectively damps forces introduced in different ranges of the characteristic due to its graduated damping characteristic. To accomplish the object, the pressure body of the bearing is divided in the radial direction into a plurality of damping areas whose damping characteristics can be adjusted independently from one another by an intermediate sleeve arranged coaxially to the inner part and the outer sleeve.

[0001] The present invention pertains to a rubber bearing with graduated damping characteristic, which comprises, in the known manner, essentially a preferably cylindrical or approximately cylindrical inner part, a tubular outer sleeve arranged coaxially around the inner part, as well as a pressure body with chambers for a damping agent, which is arranged in a fixed manner between the inner part and the outer sleeve.

[0002] Corresponding to the versatility of their use, rubber bearings must have greatly different properties in terms of their damping characteristic, and they are also stressed by the forces absorbed by them to different extents. Their damping characteristic is therefore optimized for the particular application by a suitable design of their geometry and/or by the selection of the elastomer of which the pressure body consists. Nevertheless, it is desirable to achieve a certain flexibility in manufacture in providing bearings with different properties. The bearings are also frequently subject to dynamically greatly varying conditions in terms of the forces acting on them during their practical use. It is therefore known that the bearings can be designed such that they can be adapted to the intended usc during manufacture in a simple manner or that they have a certain broad range of dynamic damping characteristics.

[0003] A design of a rubber bearing which is said to make it possible to adapt its elastic properties to different needs during the manufacture in a simple manner has already become known through DE 39 09 609 A1. This document describes a rubber bearing in which a second spring body, which is arranged at a radially spaced location from the first spring body in the gap between the inner part and the outer sleeve, is arranged in parallel to the first pressure or spring body. The second spring body is designed as a two-part body in the form of an elastomer element provided on both front sides of the bearing. Damping of the bearing, which is supported by a liquid damping agent, is not provided according to the solution according to this document. The bearing is also suitable only conditionally for use for damping vibrations with amplitudes or frequencies in different ranges of the characteristic.

[0004] A hydraulically damping rubber bearing, which brings about vibration damping in two different frequency ranges, has been known from DE 42 22 486 A1. A plurality of chambers filled with a damping liquid are formed for this purpose in the spring clement or pressure body. According to this solution, two outer chambers connected to one another via a channel in a liquid-carrying manner surround a chamber located radially farther inward. The chambers are limited against one another by rubber elastic expandable walls in their axial succession. According to the document, good insulation of higher-frequency vibrations is achieved by the inner chamber. The outer area of the spring element consequently has mainly a vibration-damping effect, whereas the inner area has a vibration-insulating effect. The comparatively great manufacturing effort for such a bearing can be considered to be disadvantageous. This is true especially concerning the liquid-tight mounting of the two vulcanized parts.

[0005] The object of the present invention is to provide a rubber bearing which has a simple design and effectively damps forces introduced in different ranges of the characteristic due to its graduated damping characteristic, while avoiding the drawbacks of the state of the art.

[0006] This object is accomplished by a bearing having the features of the principal claim.

[0007] Advantageous embodiments and variants of the bearing according to the present invention are described in the subclaims.

[0008] According to the solution being proposed, the bearing comprises. in the known manner, essentially an inner part of a cylindrical or approximately cylindrical shape, a tubular outer sleeve arranged coaxially around the inner part, as well as a pressure body with chambers for accommodating a liquid damping agent, which said pressure body is arranged between the above-mentioned parts. The basic inventive consideration on accomplishing the object is that the pressure body is divided in the radial direction into a plurality of damping areas which can be adjusted in terms of their damping characteristics independently from one another by at least one intermediate sleeve arranged coaxially to the inner part and the outer sleeve.

[0009] A design that is certainly needed most often in practice and is obvious in terms of a compromise between the best possible damping and the manufacturing effort needed therefor concerns an embodiment with two damping areas in relation to the radial direction. It is within the scope of the present invention if chambers for a damping agent are provided within both damping areas of the pressure body in this embodiment. To achieve the completely closed nature of the damping areas, i.e., damping characteristics that do not mutually affect each other, there is a liquid-carrying connection only between the chambers of one damping area. An exchange of damping agent is not possible between the different damping areas due to the inserted intermediate sleeve.

[0010] Corresponding to a possible embodiment, which can be advantageously used, e.g., for mounting the suspension arms of a vehicle, the inner damping area has a softer characteristic than the outer damping area. However, an opposite design is also conceivable for special purposes to reduce the stress on the bearing. Besides the selection of different elastomers to form the damping areas, the different damping characteristics of these damping areas can also be achieved by the use of different types of damping agents of different viscosities for filling the chambers of the damping areas.

[0011] In a special embodiment of the rubber bearing, which is also intended for special applications, at least one damping area or both damping areas has different damping characteristics with respect to forces introduced from different radial directions. Depending on the generally desired damping characteristic, this can be achieved by a corresponding shaping of the inner part or of the elastic pressure body.

[0012] According to another embodiment of the bearing according to the present invention, the damping areas have different axial lengths due to a corresponding dimensioning of the elastomer as well as of the intermediate or separating sleeve or sleeves. In a bcaring with two damping stages, the outer damping stage preferably has a shorter axial extension than the inner one.

[0013] The bearing according to the present invention makes possible an effective gradation of the damping characteristics despite its comparatively simple design and the resulting simple mounting. In the case of a characteristic that is softer toward the middle, shock and vibration loads of high frequency and low amplitude are first damped effectively by the inner damping area of the bearing. If the forces that occur become stronger, i.e., if their amplitude increases, the inner area will come to a stop. Without the presence of a second damping stage, the damping would now be brought about exclusively by the elastomer. On the one hand, there would not be such an effective damping any more as a result, and, on the other hand, the pressure body would be stressed enormously. However, the outer damping area adjusted with the harder range of the characteristic is activated when the inner damping comes to the stop due to the embodiment according to the present invention. Due to the complete uncoupling of the two damping areas, these can have very great differences in terms of their stiffness and each can be adjusted to preset frequencies separately.

[0014] The present invention will be explained in greater detail below on the basis of an exemplary embodiment. In the corresponding drawings,

[0015]FIG. 1 shows the bearing according to the present invention in an axial sectional view, and

[0016]FIGS. 2a-2 c show the components of the bearing according to FIG. 1 before mounting in an axially exploded view of the bearing.

[0017]FIG. 1 shows the bearing according to the present invention in an axial sectional view. Corresponding to the basic design of rubber bearings, the bearing has an inner part 1, which is usually made of metal. Depending on the intended use, this [inner part] may extend concentrically or, as is shown in the example being described, eccentrically around the bearing mounting hole 9. The inner part 1 is coaxially surrounded by a tubular outer sleeve 2, which is likewise made, in general, of metal. A pressure body 3 with the chambers 4, 4′, 5, 5′ for receiving a damping agent is arranged in a fixed manner between the inner part 1 and the outer sleeve 2. To achieve the graduated damping characteristic, the elastomer pressure body 3 is divided, however, unlike in the state of the art, into two closed, mutually independent damping areas 7, 8 by an intermediate sleeve 6 arranged in it.

[0018] This design is illustrated once again in FIGS. 2a-2 c by a representation of the bearing in which it is exploded in the axial direction. The individual components A, B, C and the sequence of the manufacturing steps arising during the manufacture of the bearing can be clearly recognized here. The inner part 1 and the elastomer forming the later inner damping area 7 are first connected by vulcanization, forming the chambers 4, 4′ intended to receive a damping agent, and this inner component A is also surrounded by a cage 10 in the course of the vulcanization, especially in light of the subsequent mounting. Depending on the design, a plastic clip 12 may then be pushed later over the component A, usually axially centrally, this clip being used to form specially shaped stop faces and/or as a channel carrier for a channel which connects the chambers 4, 4′ and is not shown here.

[0019] Component B is obtained by connecting the intermediate sleeve 6, which is used to separate the later damping areas 7, 8, to the elastomer forming the damping area 8, likewise while forming corresponding chambers 5, 5′. Component B is also surrounded by a cage 11. Depending on the design, a plastic clip 13 may then be pushed later over the component B, , usually axially centrally, this clip being used to form specially shaped stop faces and/or as a channel carrier for a channel which connects the chambers 5, 5′ and is not shown here.

[0020] Component C is formed exclusively by the outer sleeve 2 surrounding the entire bearing. The simple mounting of the bearing is performed by pressing the components A, B, C into one another, the components A and B being filled with the damping agent before. The different adjustment of the damping areas 7, 8 can be achieved in an advantageous manner 1 by the use of damping agents of different viscosities to fill the chambers 4, 4′ and 5, 5′. Movement of the liquid is possible only between the chambers 4, 4′ and 5, 5′ within one respective damping area 7 and 8.

[0021] If a radial force acts on the completely mounted bearing, it is damped up to a certain maximum amplitude only by the damping area 7 in case of a softer adjustment of the inner damping area 7. The pressure body 3 in the inner damping area 7 strikes the inner part 1 only in the case of strong shocks, which occur, e.g., during braking in the case of the use of the bearing in the suspension arm of a vehicle. The damping effect of the outer damping area adjusted to a harder characteristic comes into action at this moment.

[0022] List of Reference Numbers Used

[0023]1 Inner part

[0024]2 Outer sleeve

[0025]3 Pressure body, elastomer

[0026]4, 4 ′ Chamber

[0027]5, 5′ Chamber

[0028]6 Intermediate sleeve. separating sleeve

[0029]7 Damping area

[0030]8 Damping area

[0031]9 Bearing mounting hole

[0032]10 Cage

[0033]11 Cage

[0034]12 Plastic clip

[0035]13 Plastic clip 

1. Rubber bearing with graduated damping characteristic, which comprises essentially a said, preferably cylindrical inner part (1), a said tubular outer sleeve (2) arranged coaxially around the said inner part (1) as well as a said pressure body (3) with said chambers (4, 4′, 5, 5′) consisting of an elastomer for receiving a damping agent, which said pressure body is arranged in a fixed manner between the said inner part (1) and the said outer sleeve (2), characterized in that the said pressure body (3) is divided in the radial direction into a plurality of damping areas which are closed in themselves and can be adjusted independently from one another in terms of their damping characteristics by at least one said metallic intermediate sleeve (6) arranged coaxially to the said inner part (1) and the said outer sleeve (2).
 2. Rubber bearing in accordance with claim 1, characterized in that the said pressure body (3) is divided into two said damping areas (7, 8) with different damping characteristics with respect to the radial direction.
 3. Rubber bearing in accordance with claim 2, characterized in that said chambers (4, 4′, 5, 5′) for a damping agent are provided within both said damping areas (7, 8) of the said pressure body (3), wherein the said chambers (4, 4′) of the said damping area (7) and the said chambers (5, 5′) of the said damping area (8) are connected to one another by a channel in a liquid-carrying manner.
 4. Rubber bearing in accordance with one of the claim 2 or 3, characterized in that the said inner damping area (7) has a softer characteristic than the said outer damping area (8).
 5. Rubber bearing in accordance with one of the claims 2 through 4, characterized in that the said chambers (4, 4′, 5, 5′) of the said two damping areas (7, 8) are filled with damping agents of different viscosities.
 6. Rubber bearing in accordance with one of the claims 2 through 5, characterized in that one said damping area or both said damping areas (7, 8) have different characteristics with respect to forces acting from different radial directions.
 7. Rubber bearing in accordance with one of the claims 1 through 6, characterized in that the said damping areas (7, 8) have different axial lengths, wherein preferably the said outer damping area (8) adjoining the said outer sleeve (2) has the shortest axial length. 